1. Field of the Invention
The invention is directed to an improved fuel injection system for an internal combustion engine.
2. Description of the Prior Art
One fuel injection system of the type with which this invention is concerned, known from German Patent Disclosure DE 39 00 763 A1, has a high-pressure fuel pump and a fuel injection valve for each cylinder of the engine. The high-pressure fuel pump has an engine-driven pump piston defining a pump work chamber, and a communication of the pump work chamber with a relief chamber is controlled by an electrically controlled valve. The fuel injection valve has an injection valve member, by which at least one injection opening is controlled, and which is movable in an opening direction, counter to the force of a closing spring disposed in a spring chamber, by the pressure prevailing in a pressure chamber that communicates with the pump work chamber. The closing spring is braced on one end at least indirectly on the injection valve member and on the other at least indirectly on a deflection piston. The deflection piston, on its side remote from the closing spring, defines a prechamber communicating with the pump work chamber via a throttle restriction and is thus subjected to the pressure prevailing in the pump work chamber and is movable in a reciprocating motion counter to the force of the closing spring. The deflection piston is movable from an outset position, at low pressure in the pressure chamber, into a storage chamber. The pressure chamber of the fuel injection valve communicates via a conduit with the prechamber and via this chamber communicates indirectly with the pump work chamber. The communication of the pressure chamber with the pump work chamber is thus likewise effected via the throttle restriction; the dimensioning of the throttle restriction must be selected as a compromise between the dimensioning required for the function of the deflection piston and the dimensioning required for the function of the fuel injection valve.